1. Field of the Invention
This invention relates to a liquid storage tank containing a non-permanent baffle system. In particular, this invention relates to a liquid storage tank, particularly for securing to trucks or other storage systems, containing a plurality of spherical baffle balls, which substantially fill the space within the liquid storage tank.
2. Description of Related Art
Trucks, particularly tank trucks, are widely used for transporting many types of liquids, particularly water and water-based chemicals. Many of the tanks used on these trucks have a storage capacity of at least 100 gallons, and sometimes as much as 3,000 gallons or more. With a weight of over 8 lbs. per gallon for water, the overall weight of a load of water in one of these tanks can be 12 tons or more.
Tank trucks travel on conventional highways and are required to be driven at conventional speeds. The inertial force present in a load of such liquids contained within one of these tanks can be extremely high. When it is necessary to stop these vehicles, this inertial force, which is enhanced by the sudden shifting of the liquid in the tank, can have a serious destabilizing effect on the vehicle. In addition, the continual sloshing movement of the liquid within the tank can damage the tank by putting pressure on its welds or joints. An especially dangerous situation can arise when a vehicle with such a tank is driven on a wet or icy road.
To reduce the destabilization caused by the movement of these liquids within the tank, the tank should be filled to capacity. However, this is not always possible or even desirable.
One proposed solution to this problem is the installation of fixed baffles within the interior of the tank which are secured at right angles to the direction of anticipated movement of liquids contained within the tank. Such baffles form smaller compartments within the tank, limiting the distance that the liquid can slosh within the tank. Examples of tanks containing this type of baffles are disclosed in U.S. Pat. Nos. 4,251,005; 2,011,161; and 1,909,734. In addition, circular shaped, dished baffles secured within a tank on a water truck designed to attenuate forces directed at them are disclosed in U.S. Pat. No. 4,789,170.
The number of baffles required and their structure depends on the size and capacity of the tank in which they are incorporated, the density of the liquid being carried, the anticipated speed of the vehicle, and other such considerations. It has been determined, however, that while fixed baffles are frequently helpful, they do not completely ameliorate the adverse effect of movement of the liquid within the tank. These fixed baffles merely create a series of smaller tanks, resulting in the same types of problems only in several smaller tanks. Sloshing of the liquid in these smaller tanks and the momentum of the load generated by movement of the liquid contained within the tank still exists.
As an alternative to the use of fixed baffles within a tank, U.S. Pat. No. 3,784,050 discloses a floating baffle system comprising a plurality of individual spherical objects, each of which is designed to float in the liquid and absorb the kinetic energy present within the liquid by collision of those objects among themselves. This baffle system is specifically designed for utilization in a fuel tank but the system is not designed to fill the tank to capacity. In addition, the individual spherical objects are required to have a specific density which is only slightly greater than the specific density of the fuel contained within the tank. At rest, they sink to the bottom of the tank and upon agitation, they distribute themselves throughout the tank. The tank is designed to be built with these spherical members already present in the tank.
Another type of liquid transportation system utilizes solid collapsible containers, such as ordinary tennis balls, as baffles within a tank to dissipate the "water hammer" effect caused by the sudden deceleration of a mass of liquid, is disclosed in U.S. Pat. No. 5,303,843. However, such solid containers will occupy a significant portion of the space within the tanks.
U.S. Pat. No. 3,687,329 discloses a liquid storage system containing a plurality of solid, buoyant bodies or spheres which float on the surface of the storage system. This system is designed to reduce the fire risk of the flammable liquids contained in the storage tank. However, these buoyant bodies also occupy a significant portion of the space within the tank. See also U.S. Pat. No. 3,192,877.
While the above-referenced devices are helpful in the attenuation of inertial forces of liquids contained within tanks, there are still a number of deficiencies in these systems. In addition, the above-referenced baffle systems are conventionally built into the tank during construction of the tank. Further, the prior art baffle systems cannot be modified to accommodate changes in the use of the tank.
It is accordingly an aspect of this invention to disclose a liquid storage tank and baffle system.
It is a further aspect of this invention to disclose a liquid storage tank and baffle system utilizing a plurality of spherical baffle balls which can be introduced into a conventional storage tank after the tank has been constructed.
It is a still further aspect of the invention to disclose a liquid storage tank and baffle system wherein baffle balls of the baffle system substantially fill the space within the liquid storage tank. It is a still further aspect of the invention to disclose a liquid storage tank and baffle system wherein baffle balls of the baffle system are sized to just fit within the opening in the storage tank used for the introduction of the liquid into the liquid storage tank.
It is a still further aspect of the invention to disclose a liquid storage tank and baffle system wherein the baffle balls occupy no more than about five percent (5%) of the space contained within the liquid storage tank.
It is a still further aspect of the invention to disclose a liquid storage tank and baffle system wherein each spherical baffle ball of the baffle system is produced in separate pieces which are joined together for introduction into the liquid storage tank.
It is a still further aspect of the invention to disclose a liquid storage tank and baffle system wherein the spherical baffle balls used in the system contain support ribs molded into the surface of the baffle balls to provide structural support.
These and other aspects of the invention can be determined by an analysis of the disclosed liquid storage tank and non-permanent baffle system and the design for the individual components of that system which are disclosed by the present invention.